1. Field of the Invention
The present invention relates generally to drilling devices and screwdriver devices and more particularly, to drill bits and screwdriver blades.
2. Description of the Prior Art
Drilling devices are well known in the art. Commonly, drilling devices are powered by electric motors. Alternatively, drilling devices are manually powered. Generally, a drilling device includes two main components: a driving device and a driven device. The driving device generally includes some kind of chuck for securing the driven device. The driven device is most often referred to as a drill bit.
The drill bit generally has a number of distinct portions. There is a tang portion that fits into the chuck. A shank portion extends away from the tang portion to a twist portion. At the far end of the twist portion, the head portion is located. For a drill, the head portion generally includes a cutting element.
Often a power screwdriver will include a bit that is very similar to a drill bit. That is, a driven member includes a tank portion and a shank portion. The head portion, instead of having a cutting element, will have a screwdriver blade.
Throughout the years, a number of innovations have been developed relating to drill bits. The following U.S. patents are representative of some of those innovations: 3,589,826; 4,992,009; 5,024,566; 5,049,010; and 5,061,127.
More specifically, U.S. Pat. Nos. 3,589,826, 4,992,009, and 5,061,127 disclose drill bits having variations in the cutting head. In each of these devices, the cutting head, the twist portion, the shank, and the tang are a unified, integrated structure. This means that when the cutting head wears down or gets dull, the entire drill bit, including the twist portion, the shank, and the tang must be disposed of and replaced along with the worn cutting head. This is wasteful for a number of reasons. It is wasteful of metal because the twist portion, the shank, and the tang must be replaced even if they are perfectly fine. It is wasteful of money because perfectly fine used components must be discarded, and new components must be paid for along with the new cutting head. In this respect, it would be desirable if a drill bit device were provided which did not necessitate replacement of a twist portion, a shank portion, and a tang portion when the head portion was replaced.
U.S. Pat. No. 5,024,566 discloses a compound drill bit that contains two individual interchangeable drill bit heads retained in a common housing. Each drill bit head has an associated handle and slot for guiding the respective handle and drill bit head into and out of drilling position. The structural support for each drill bit head with the common housing is relatively flimsy because of the complexities of the selection structures for selecting the desired drill bit head. Moreover, only two selectable drill bit heads are disclosed. The limited number of interchangeable drill bit heads is limited by a number of factors: the complexities of the interior structures of the drill bit head housing; obtaining rotary dynamic balance for the complex drill bit housing and the multiple drill bit heads contained therein. In this respect, it would be desirable if a drill bit device provided the benefits of interchangeable drill bit heads without employing a complex housing that contains a plurality of interchangeable drill bit heads that is difficult to manufacture and to dynamically balance.
U.S. Pat. No. 5,049,010 discloses a metal cutting tool that includes two cutting members, a relatively large diameter, cylindrical cutting member and a relatively small diameter cylindrical pilot bit that is centrally located with respect to the large diameter cylindrical cutting member. The cylindrical pilot bit is relatively short and has two equal but opposite cutting ends separated from one another by a cylindrical shank which includes a planar notch that receives a set screw for locking the cylindrical pilot bit in position inside the large diameter cylindrical cutting member. In this device, the engagement between the set screw and the planar notch absorbs large torsional forces between the cylindrical drill bit and the large diameter cylindrical cutting member and prevents the cylindrical drill bit from rotating independently of the large diameter cylindrical cutting member. Moreover, the engagement between the set screw and the planar notch prevents the cylindrical pilot bit from moving longitudinally with respect to the large diameter cutting member. In other words substantially all the stresses (both torque and longitudinal stresses) that exist between the large diameter cylindrical cutting member and the small diameter cylindrical pilot bit are absorbed by the engagement of the set screw with the planar notch. The surface area of engagement of the set screw with the planar notch is very small. In this respect, the absorption of large torsional stresses on such a small area of engagement causes a large amount of wear, tear, and fatigue on the small area of engagement. In this respect, it would be desirable if a drill bit device were provided which provided a relatively large surface area of engagement between a replaceable drill bit head and its supporting structure so that torsional stresses between the replaceable drill bit head and its supporting structure is distributed over a relatively large surface area.
The discussion above relating to torsional stresses for drill bits also apply to screwdriver blades. Similarly, then, it would be desirable if a screwdriver blade device were provided which provided a relatively large surface area of engagement between a replaceable screwdriver blade head and its supporting structure so that torsional stresses between the replaceable screwdriver blade head and its supporting structure is distributed over a relatively large surface area.
Numerous types of drill bits are manufactured to cut numerous types of materials. To an expert, the shape of the cutting head may indicate the type of material that the drill bit is designed to cut. However, many people do not have the knowledge that would permit them to determine the kinds of material that can be drilled by a visual inspection of the cutting head of the drill bit. In this respect, it would be desirable if a drill bit device were provided which had some kind of instructive indicia which indicated to the user which type of materials the drill bit is designed to cut.
Moreover, drill bits vary as to the type of material from which they are fabricated. Some drill bits are made of expensive, very hard metals. Other drill bits are made of more inexpensive softer metals. If a drill bit made of a relatively soft metal is used to bore into a very hard metal stock, the soft-metal drill bit will become dulled very prematurely. Often one is not able to assess the durability of a drill bit simply by visually inspecting the shape of the cutting head. A hard metal drill bit and a soft metal drill bit may have the same shaped cutting head. In this respect, it would be desirable if a drill bit device were provided that had some kind of instructive indicia which indicated to the user which type of material the drill bit is fabricated from.
As mentioned above, drill bits and screwdrivers have much in common. For example, to be used with a powered driver, they both have a tang, a shaft, and a head portion. In this respect, it would be desirable if a drill bit device were provided which had common tang and shaft portions and which had interchangeable heads that could be interchanged between cutting heads for a drill and blade-containing heads for a screwdriver.
Moreover, screwdriver blades vary as to the type of material from which they are fabricated. Some screwdriver blades are made of expensive, very hard metals. Other screwdriver blades are made of more inexpensive softer metals. If a screwdriver blade made of a relatively soft metal is used on a screw that is torqued tightly, the soft-metal screwdriver blade may become dulled very prematurely. Often one is not able to assess the durability of a screwdriver blade simply by visually inspecting the screwdriver blade. A hard metal screwdriver blade and a soft metal screwdriver blade may both look very much alike. In this respect, it would be desirable if a screwdriver blade device were provided that had some kind of instructive indicia which indicated to the user which type of material the screwdriver blade was fabricated from.
Often a worker would like to carry a large number of drill bits and screwdriver blades to a job site to have versatility in selection of respective drill bits and screwdriver blades. Sets of drill bits and screwdriver blades are often stored and carried in portable containers that are hand carried to the job site. For purposes of convenience and to free a worker's hands for other tasks, it would be desirable if a set of drill bits or screwdriver blades could be carried by a worker in belt device.
Often, sets of drill bits and screwdriver blades are carried in containers that include a plurality of receiver portions for receiving respective drill bits and screwdriver blades. However, contact between respective receiver portions and the respective drill bits and screwdriver blades if often very insecure. As a result, individual drill bits and screwdriver blades often separate from their respective receiver portions, and often a confusing, messed up array of drill bits and screwdriver blades results. In this respect, it would be desirable if a drill bit device were provided which included receiver portions for drill bits and screwdriver blades that included means for retaining the respective items in their respective receiver portions.
Thus, while the foregoing body of prior art indicates it to be well known to use a variety of types of drill bits and a variety of types of screwdriver blades, the prior art described above does not teach or suggest an interchangeable head boring or driving apparatus which has the following combination of desirable features: (1) does not necessitate replacement of a twist portion, a shank portion, and a tang portion when the head portion is replaced; (2) provides the benefits of interchangeable drill bit heads without employing a complex housing that contains a plurality of interchangeable drill bit heads that is difficult to manufacture and to dynamically balance; (3) provides a relatively large surface area of engagement between a replaceable drill bit head and its supporting structure so that torsional stresses between the replaceable drill bit head and its supporting structure is distributed over a relatively large surface area; (4) has some kind of instructive indicia which indicates to the user which type of materials the drill bit is designed to cut; (5) has some kind of instructive indicia which indicates to the user which type of material the drill bit is fabricated from; (6) has common tang and shaft portions and which has interchangeable heads that can be interchanged between cutting heads for a drill and blade-containing heads for a screwdriver; (7) has a screw driver blade device has some kind of instructive indicia which indicates to the user which type of material the screw driver blade is fabricated from; (8) can carry a set of drill bits or screwdriver blades in a belt device; (9) includes receiver portions for drill bits and screwdriver blades that includes means for retaining the respective items in their respective receiver portions; and (10) provides a relatively large surface area of engagement between a replaceable screwdriver blade head and its supporting structure so that torsional stresses between the replaceable screwdriver blade head and its supporting structure is distributed over a relatively large surface area. The foregoing desired characteristics are provided by the unique interchangeable head boring or driving apparatus of the present invention as will be made apparent from the following description thereof. Other advantages of the present invention over the prior art also will be rendered evident.